What is Light Pollution? • Sky glow: bright halo over urban, suburban, and some rural areas at night due to bad outside lighting • Glare: light that shines horizontally and directly into a person’s eyes • Light trespass: unwanted artificial light (floodlights, security lights, streetlights) that spills onto property which would otherwise be dark • Over-illumination: artificial lighting that is brighter and on longer than required for a specific activity
Night-Sky-Friendly Lighting • can be aesthetically attractive & enhance neighbourhood appearance • allows people to move around safely – they are not blinded by glare • keeps light on ground - where it is needed • prevents light trespass onto other’s property and into their homes • saves energy, money, and the environment • keeps night sky unpolluted (www.starrynightlights.com) Our Vanishing Night. National Geographic (November 2008) Can We Win the War Against Light Pollution? Astronomy (February 2009) for more information: www.darksky.org // www.rasc.ca
Light Pollution is one of the fastest growing & most pervasive forms of environmental pollution, according to many environmentalists, naturalists, and medical researchers. Scientific research suggests that light pollution can have lasting adverse effects on both human and wildlife health.
Why is Light Pollution so bad? It disrupts biological rhythms! • Plants and animals, including humans, have 24-hour (circadian) biological rhythms under the control of the daily light-dark cycle. • Light pollution hurts diurnal & nocturnal species by disrupting: - Physiological rhythms, including hormone levels - Behaviour patterns (feeding, predator avoidance, courtship, migration) - Reproduction, leading to population declines & secondary effects on other species (due to the interdependence of plants & animals) - Ecosystems Ecological Consequences of Artificial Night Lighting. Rich, Longcore (eds.) (2006) Environmental Health Perspectives v117 (2009) for more information: www.darksky.org // www.rasc.ca
Light Pollution and Environmental Health • Insects flying around night lights become too exhausted to feed and reproduce, causing their populations to decline.1 • Insects are primary food source for many predators (e.g., bats, birds, lizards, frogs). Altering the balances compromises the food chain. • Bright lights disarm flying moths & other insects of their bat evasion system, tipping this evolutionary arms-race in favour of the predator! • Bright lights confuse navigation along migratory routes. • Declines in populations of moths, spiders, sparrows, and amphibians have been correlated with light pollution in the UK & elsewhere.2 • Hatchlings of seed-eating as well as other birds need the protein from insects and spiders in their diet to survive. • Insects are essential pollinators for many plants. Their decline leads to decline of many plant species – crops, shrubs and trees that provide habitat for many other species, ornamental plants, etc. 1 2
The 50,000 streetlights in Zürich estimated to kill more than 1 million insects/night. In UK, large moth species declined by 1/3 in 28 years & some species by up to 98%.
Attenborough (2005) Life in the Undergrowth for more information: www.darksky.org // www.rasc.ca
Bring back the Night Sky A child born today has less than a one in ten chance of ever experiencing a dark sky. From time immemorial, humans have marvelled at the night sky, and found inspiration, knowledge, understanding, and pleasure in its beauty... Light Pollution disrupts natural patterns of light and dark. It changes animal behaviors (confuses navigation, alters competition & predatorprey interactions) and adversely affects physiology and reproduction.
Light Pollution contributes to lower water quality by preventing zooplankton from feeding on algae, which grow more in light! Light Trespass from Outdoor Lighting has Indoor Effects! Excessive artificial light can affect production of hormones, disrupt sleep patterns, and hav